Chair supporting structure



Ivimffch 18, 1947.

E. C. BOOTH CHAIR SUPPORTING STRUCTURE Filed Aug. 31, 1944 INV-ENT OR.ch/2z 6,' Booz-,93,

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Patented Mar. 18, 1947 CHAIR SUFPORTING STRUCTURE Earl C. Booth,Columbus, Ind.,

assignor to Noblitt-Sparks Industries, Inc., Columbus, 1nd.,

a corporation of Indiana Application August 31, 1944, Serial. No.552,142

9 Claims.

My invention relates to a metal chair, and more particularly to thatform of chair embodying a pair of U-shaped members each of which isformed of metal tubing and has a lower horizontal stretch adapted torest on the licor or other supported surface, an intermediate stretchextending generaly vertically and secured to a front corner of the seat,and an upper horizontal stretch which is secured at its rear end to thechair-back and which provides a chair-arm. My invention is particularlyconcerned with a means for interconnecting the rear ends of the lowerhorizontal stretches of the respective side members.

It is the object of my invention to provide a means for interconnectingthe rear ends of the respective lower side-member stretches which willbe attractive in appearance, which will provide iirm joints, and whichwill not unduly reduce the stability of the chair.

In carrying out my invention in its preferred form I provide a tubularcross member or stretcher the ends of which are telescopically connectedrespectively to the rear ends of the lower sidemember stretches. Becausethe stretcher will be disposed generally perpendicularly with respect tothe lower side-member stretches, it will be necessary, in order toeffect the telescopic interconnection, to bend either the ends of thestretcher at right angles to the body thereof or to bend similarly therear end of each lower side-member stretch. For a purpose to behereinafter made apparent, it is desirable to make such bends about assmall a radius as possible; and to eiect this result, I rst collapse thetube for a distance and then coniine the bend substantially to suchcollapsed portion.

The accompanying drawing illustrates my invention: Fig. 1 is a sideelevation of an erected chair; Fig. 2 is a fragmental plan view of therear` end of the chair-base; Fig. 3 is a fragmental view similar to Fig.2 with portions of the tubing being shown in section; Fig. 4 is avertical section on the line 4-4 of Fig. 3; and Fig. 5 is a view similarto Fig. 2 illustrating a modied construction in which the bends areprovided in the ends of the stretcher rather than in the ends of thelower stretches of the side member.

The chair illustrated in Fig. 1 comprises a seat I0 and a back Il, hereshown as formed of a single piece of sheet metal in accordance with thedisclosure of my prior Patent No. 2,881,718, granted July 31, 1945. Ateach side of the chair there is provided a U -shaped side member formedof metal tubing bent to provide a lower horizontal stretch i2, agenerally vertical intermediate stretch I3, and an upper horizontalstretch lll. The intermediate stretch I3 is secured to the front cornerof the seat lll, as by means of a bolt or screw l5, while the rear endof the upper horizontal stretch I il is secured to the back II, as bymeans of a screw or bolt I6. If desired, the lower horizontal stretch i2of each side member may be arched slightly as indicated in Fig. 1.

In the construction illustrated in Figs. 2, 3 and 4, the rear ends ofthe horizontal stretches l2 of the two side members are bent throughinto substantial alinement with each other and telescopically receivethe ends of a cross-member or stretcher ill. As shown, the stretcher 2Qis formed of tubing having a diameter equal to that of the side members,and its ends are reduced in diameter to permit its reception within theends of the side members. The particular form of joint employed betweeneach end of the stretcher and the adjacent end E8 of the associated sidemember is immaterial, but I prefer the type of joint illustrated becauseof its relatively attractive appearance.

To prevent separation of the stretcher 20 from the side members when thechair is erected, a bolt 22 is passed through the telescopicallyassociated ends. Desirably, the metal surrounding the holes in the tubewalls through which the bolt 22 passes is displaced inwardly of the tubeto form nesting frusto-conical flanges. Desirably also, the underside ofthe bolt-head is frusto-conical, and a frusto-conical washer 23 isdisposed beneath the nut 24 at the opposite end of the bolt. As a resultof this construction, when the bolt is tightened, the conical flanges onthe inner and outer tubes are forced tightly together, thus preventingrelative rotation of the tubes.

It will be obvious that the stability of the chair, especially when theperson sitting in it tends to lean backward, will depend upon the radiusof the bends at the ends of the horizontal stretches l2. The greaterthis radius, the less will be the width of the base at itsrear end, andthe less will be the stability of the chair against lateral tipping. Itis therefore desirable to bend the rear ends oi the side-memberstretches l2 about as small a radius as possible. However, the bendingof metal tubing about a small radius is diicult because of the tendencyof the tube to collapse and wrinkle.

To produce a bend of satisfactorily small radius, while stillmaintaining an attractive appearance, I employ the expedient bestillustrated in Figs. 3

and 4. As will be clear from those figures, and especially from thedotted-line showing of Fig. 3, we rst collapse the tubing for a distanceequivalent to that over which it is to be bent, forcing that wall of thetube which will be on the inside of the bend in contact with theopposite wall. To avoid abrupt bends in the tube-collapsing operationthe tube is formed beyond each end of the completely collapsed portionwith a concave groove 2'.i or gradually decreasing depth. After the tubeis collapsed in the manner indicated, the collapsed portion is bentthrough an angle of 90, as will be clear from Figs. 2 and 3. In thisbending operation, the collapsed portion of the tube is desirably formedtransversely so that its exterior curvature will correspond in radius tothe uncollapsed portion of the tube, as is shown in Fig. 4.

By first collapsing the tube and then bending it, I am able to avoid anyunsightly Wrinkling of metal, and thus l produce a bend which is ofattractive appearance and still possesses the desirable small radius.The radius of horizontal curvature of the outer tube-wall over theextent of the bend can be as small as or even smaller than the diameter'of the tube and preferably is no more than twice such diameter.

In the modiied construction illustrated in Fig. 5, the 9 bends areprovided in the'ends of the s retcher Eil', instead of in the ends ofthe ho1'i sontal side-mernber stretches Otherwise, the construction issubstantially the same as that previously described.

While I prefer to maize the tubular side members separate piecesinterconnected at their rear ends by the stretcher 2i? or EU. theadvantages in respect to stability obtained through the practice of myinvention exist irrespective of the separate character of the sidemembers and stretcher.

I claim as my invention:

1. In a chair, a supporting structure having a base portion includingtwo horizontal tubular members disposed in generally parallelrelationship at the sides of the chair and a transverse stretcher, saidmembers and stretcher being of circular cross-section, said tubularmembers being provided with bends which bring their ends into alinementwith each other and said stretcher being telescopically associated withand secured to said alined member-ends, the Wall Vof each tubular memberon the inside of the bend therein being displaced outwardly into contactwith the tube-wall on the outside of the bend, the two contacting tubeWalls being curved in cross-section with the radius of curvature of theouter surface of the outer tube-wall conforming substantially to theradius of the undistorted outer surface of the tube-wall.

2. IThe invention set forth in claim 1 With the addition that the innerwall of the tubular member for a distance in each direction from saidbend is displaced inwardly of the tube to form a groove of graduallydecreasing depth.

3. The invention set forth in claim 1 with the addition that the radiusoi `horizontal curvature of the outer surface of the bent portion ofsaid tubular member is no greater than approximately twice the diameterof the tubular member.

4. In a chair, a supporting structure having a base portion includingtivo horizontal members disposed in generally parallel relationship atthe sides of the chair and a transverse stretcher, said members andstretcher being of circular cross-section, said two members being joinedrespectively to the ends of said stretcher at points adjacent-I the rearcorners of said base portion, one of the two elements joined at eachrear corner of the base portion being tubular and being provided with ahorizontal bend to bring its end into alinement with the other of suchelements, the tube-Wall on the inside of said bend being displacedoutwardly into contact with the tubewall on the outside of the bend, thetwo contacting tube walls being curved in cross-section with the radiusof curvature of the outer surface of the outer tube-wall conformingsubstantially to the radius of the undistorted outer surface of thetube-Wall.

5. The invention set forth in claim 4 with the addition that the innertube-Wall for a distance in each direction from said bend is displacedinwardly of the tube to form a groove of gradually decreasing depth.

6. The invention set forth in claim 4 with the addition that theexternal radius of said bend is no greater than approximately twice thediameter of the tube.

7. In a chair, a supporting structure having a base portion includingtwo horizontal members disposed in generally parallel relationship atthe sides of the chair and a transverse stretcher, said members andstretcher being of circular cross-section, said stretcher being tubularand bent adjacent its ends to bring such ends into alinementrespectively with the rear ends of said horizontal members, each end ofsaid stretcher being telescopically associated with and secured to therear end of such adjacent horizontal member, the Wall of said stretcheron the inside of each bend being displaced outwardly into contact withthe tube-Wall on the outside of the bend, the two contacting tube wallsbeing curved in cross-section with the radius of curvature of the outersurface of the outer tube-Wall conforming substantially to the radius ofthe undistorted outer surface of the tube-Wall.

8. The invention set forth in claim 7 with the addition that the innertube-wall for a distance in each direction from said bend is displacedinwardly of the tube to form a groove of gradually decreasing depth.

9. The invention set forth in claim 7 with the addition that theexternal radius of said bend is no greater than approximately twice thediameter of the tube. y

EARL C. BOOTH.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 2,303,039 Gilln'son Nov. 24, 19422,017,170 Smith Oct. 15, 1935 1,385,630 Ronan Nov. 1 1932 2,011,067McKee Aug. 13, 1935 1,988,860 Smith Jan, 22, 1935 2,071,084 Nolan Feb.16, 1937 2,346 449 Noblitt et al Apr. 11, 1944 2,044,862 Smith June 23,1936 1,542,983 Bergmann June 23, 1925 2,192,560 Riemenschneider Mar. 5,1940 FOREIGN PATENTS Number Country Date 129,697 Austrian June 23, 1925451,909 British Aug. 13, 19,36

